Pick-proof locks

ABSTRACT

A cylindrical housing contains a lock cylinder having a stack of lock plates rotatably positioned therein. When a key is inserted into the lock and turned, the lock plates rotate and align themselves to form a continuous groove that accepts and receives a locking pin otherwise normally lodged in a juxtaposition groove in the cylindrical housing. This acceptance of the pin enables the lock cylinder to rotate within the housing and thereby move the locking mechanism to the unlocked position. A hardened cap and cover plate make the lock almost indestructible for all practical purposes.

United States Patent [191 La'dewig July 2, v1974 [54] PICK-PROOF LOCKS 3,444,712 5/1969 Greenvvald 70/454 x ,550,4 1 l2 I970 N [761 Inventorl Werner Ladew'g, 4 BOX 3681 956 8/1972 70/366 95, St. Charles, II]. 60176 v [22] Filed: Mar. 9, 1972 Primary Examiner-Robert L. Wolfe i a I A 9 w a W pp No: 233,210 gltetlrgfmey Agent or Firm lter elss hitesel &

[52] U.S. Cl 70/366, 70/373, 70/417, [57] ABSTRACT 70/419 770/454 A cylindrical housing contains a lock cylinder having a [51] Int. Cl E05b 9/04, E05b 15/16 Stack of lock ates rotat bl d th [581 Field of Search 70/366 365 417 418 P a y 7O/4l9 421 452 454 When a key 15 inserted into the lock and turned, the

51 423 14 lock plates rotate and align themselves to form a continuous groove that accepts and receives a locking pin otherwise normally lodged in a juxtaposition groove in [5 6] References cued the cylindrical housing. This acceptance of the pin en- UNITED STATES PATENTS ables the lock cylinder to rotate within the housing 1,422,516 7/1922 Augenbraun 70/417 and thereby move the locking mechanism to the unl,484,757 2/1924 Con ey 70/417 locked position A hardened cap and cover plate make 5 3 10/1950 Young 70/366 the lock almost indestructible for all practical pur- 3,06l,455 10/1962 Anthony t l5l/l4.5 poses 3,l30,573 4/1964 Hines i 70/4l7 3,319,443 5/1967 Perlick 70/421 12 Claims, 15 Drawing Figures AIEN'IEBJM' 2 m4 SHEEI 2 BF 2 1 AIBCDEFGH J FIGJI FIG.I4

PICK-PROOF LOCKS This invention relates to very low cost, pick-proof locks and, more particularly, although not exclusively, to locks for the coin boxes of coin-operated machines.

Almost any lock can be picked if enough time and effort is used. However, within reason, some locks may be so difficult to pick that they become pick-proof, as a practical matter. Likewise, any lock may be destroyed if enough force is used to destroy it. However, the lock may be made strong enough to become almost indestructible, as a practical matter.

The problem is to make a pick-proof, indestructible lock at such a low cost that it may be used on the coin boxes of coin-operated machines. However, the lock should also be sturdy enough to be used on equally important devices, such as lock boxes, small safes, and the like.

Accordingly, an object of the invention is to make new and improved low cost locks. Here an object is to make locks which are almost pick-proof and virtually indestructible, within the environment of their normal use. In this connection, an object is to provide a lock of such low cost that it finds use in a mass market and yet of such high quality that it may be used in demanding installations.

Another object is to make a lock of the described type without requiring substantial amounts of special purpose tooling. Here an object is to make the lock on general purpose machinery, such as screw machines and punch presses.

In keeping with one aspect of the invention, these and other objects are accomplished by a use of a cylindrical housing having a lock cylinder rotatably mounted therein. A stack of lock'plates are positioned inside the cylinder. When a key is inserted into the lock and turned, the lock plates rotate and align themselves to form a continuous groove that accepts and receives a locking pin normally lodged in a juxtaposition groove in the cylindrical housing casing. Usually the pin in the housing groove prevents rotation of the cylinder, and that is the locked condition. However, when the pin is received in the aligned groove, the pin movement enables the lock cylinder to rotate within the housing and thereby move the locking mechanism to the unlocked position. A hardened cap and cover plate make the lock almost indestructible for all practical purposes.

A preferred embodiment of the invention is shown in the attached drawings wherein:

FIG. 1 is an exploded view of the inventive lock;

FIG. 2 is a cross-sectional view of the lock cylinder, taken along line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional bottom view of the lock cylinder, taken along line 33 of FIG. 1;

FIG. 4 is a cross-section of the outside lock housing, taken along line 4-4 of FIG. 1;

FIG. 5 is a cross-sectional view of an exposed cap of hardened material, taken along line 5-5 of FIG. 1;

FIG. 6A is a plan view of the bottom of an assembled lock, taken along line 6-6 of FIG. 1;

FIG. 6B is a plan view of the top of the assembled lock, with the escutcheon or nose piece removed, taken along lines 6B6B of FIG. 1;

FIG. 7 is a plan view of a hardened cover plate for the lock assembly;

FIGS. 8 and 9 are plan views of two exemplary lock plates used in the cylinder;

FIG. 10 is an exemplary plan view of seven alternative lock positions for making any of the individual lock plates;

FIG. 11 is a plan view of a key for the inventive lock;

FIG. 12 is an exemplary series of cross-sectional views taken along planes A-F, respectively, of FIG. 11; and I FIGS. 13 and 14 are schematic showings of a cover plate for positioning over the inventive lock.

As best seen in FIG. 1, the major elements of the lock are an escutcheon or nose piece 20, a cylindrical lock housing 21 having a smooth bore therein, a plurality of lock plates 22, a lock cylinder 23 dimensioned to fit into and rotate within'the bore of the housing 21, a locking pin 24, a stop plate 25, a control cam 26, and a pair of attachment nuts 27, 28. I

The escutcheon or nose piece 20 is made with a somewhat generally hemispherical or hemiellisodial cross-section (FIG. 5). This is the portion of the lock which is exposed to view when the locked door, box, or the like, is closed. Thus, if someone attempts to grip the exposed part 20, as by a pair of pliers, for.example, the jaws of the pliers will tend to slip off the rounded dome shape. The underside of piece 20 has a threaded nutlike cavity. Therefore, piece 20 screws onto the open end of the housing 21 to complete the assembly. When the assembly is so completed, the piece 20 is cemented or soldered to the housing, and one or more pins 30 are staked through the piece 20 and the housing 21 to preclude disassembly of the lock.

Inside the lock housing 21 is the lock cylinder 23, which is dimensioned to rotate freely within the smooth bore of the lock housing 21. The bottom of the lock cylinder 23 terminates in a threaded shaft 31 which is somewhat flattened on two sides 31a, 31b (FIG. 6A) to form a key member for turning a latch means. A bearing is formed at 33 to enable the cylinder to rotate in a cooperating bearing seat 34 (FIG. 4) in housing 21. Formed in cylinder 23 is an open segment A (FIGS. 1 and 68) extending over an arc of about to Diametrically opposite the open segment A is a locking groove 35 for receiving a locking pin 24.

The bottom of the'cylinder 23 ends in a massive wall 36 (FIG. 2) which provides strength, may be drilled and reamed to provide space for additional locking plates, and provides a recess 37 in which a hardened, wear resistant means 38 may be lodged. The wear means 38 is here shown as a ball bearing fastened in the recess 37, as by means of an epoxy cement, for example. The advantages of this use of a ball bearing are that it prevents drilling out the lock; it is readily available at a very low cost; and it prevents wear from keys or other objects which may be properly placed in the lock.

The inside of the cylinder 23 is a smooth bore for receiving a stacked plurality of lock plates 22. Each of the lock plates (FIGS. 8, 9, 10) comprises a circular disk 41 having a diameter which rotatably fits within the smooth bore. A crescent keyhole 42 is formed coaxially about the center point of the disk. A lug or stop member 43 projects outwardly from each disk and fits into the segment of are A, cut from the lock cylinder 23. Thus, the disk 41 may rotate over the arc A, as far as the two edge walls 45, 46 of cylinder 23.

exemplary lock plate with the No. 4 notch 50 posi-- tioned at 90, and FIG. 9 shows another exemplary lock plate with the No. 3 notch 51 positioned at 75. By the use of a plurality of plates having randomly positioned notches, almost an infinite combination of plate positions may be provided.

As shown at 22 and 55 (FIG. 1), a stack of lock plates is dropped into the smooth bore of the lock cylinder 23. Each of the lock plates is separated from its neighbor plate by a Belleville spring 56 having a flange with a segment angle A and a notch 58 positioned opposite groove 35 in lock cylinder 23. The radial edges of spring segment A fit against the shoulders 45, 46 of the cylinder 23 so that the notch 58 is always aligned with the locking groove 35.

The lock operation should now be clear. A key is fitted through the crescent-shaped keyholes 42 and rotated to align the notches 50-53 on each of the lock plates 22, 55. This alignment forms a groove which accepts and receives the locking pin 24. When the pin 24 moves into the groove formed by the aligned lock plates, the cylinder 23 is free to rotate in the smooth bore of housing 21. Before the pin 24 so moves into the aligned groove, it is pushed outwardly into one of two grooves 60 formed in the inside wall of the housing bore. Thus, in this outward position, the pin 24 must occupy both grooves 35 and 60 so that the lock cylinder 23 cannot turn in the housing 21. When the notches in all of the lock plates are aligned to allow the pin 24 to escape from groove 60, the cylinder can so turn.

The top plate 62 is similar to a lock plate except that it has two notches 63, 64 which enable an aligned notch to be positioned adjacent the lock'cylinder groove 35 when the key is turned either left or right.

The escutcheon or nose piece and the top plate 62 are made of a suitably hardened metal which is difficult to drill or cut with normal tools. While it may be possible to damage or open the lock with suitable power tools, it is not easily possible to so damage it by the types of tools likely to be used by the usual sneak thief who might try to pry open a coin box.

After the lock plates, Belleville springs and cover plates are assembled in the lock cylinder 23, the assembly is slid into the bore in housing 21. The locking pin 24 is captured within the grooves 35, 60. The bearing surfaces 33, 34 come together to enable the locking cylinder 23 to turn within the bore of the housing 21.

Next, the escutcheon or nose piece 20 is turned on to the housing 21 with a suitable cement, such as epoxy, in threads. When a tight assembly is completed, a stake is fitted through holes 66, 67 in the piece 20 and the housing 21.

At thistime the threaded shaft 31 projects out of the bottom of the housing 21. As seen in FIGS. 3 and 6A, opposite sides of the shaft are flattened. A stop plate 25 fits over the shaft 31 to cooperate with a projection 68 on housing 21 for stopping and limiting the rotational motion of the cylinder. A cam plate 26 is next placed on the shaft 31. Then a locking nut 27 is spun tightly onto the shaft 31. A long actuation arm B on the cam 26 rotates about the axis formed by the center of the shaft 31. Thus, a latch mechanism may be operated by turning the lock.

The housing 21 has parallel faces 69 which fit against mating flat faces in a cabinet or door receiving the lock.

Thereafter, a nut 28 is spun onto the threads on the outside of the housing 21 to lock it into position.

FIGS. 11, 12 disclose the key used to unlock the inventive device. In greater detail, the shank of the key is a half tube having a crescent cross-section fitting into the keyhole 42. The length of the key is divided into successive discrete areas corresponding to the positions of the lock plates. One edge of the key is cut, as shown in FIGS. 12A-F, to have segments for individually operating such lock plate. These c'ut sections complement the notch positions seen in FIG. 10. Thus, for example,

if the plate of FIG. 10 is rotated in a clockwise direction, it would have to turn a maximum distance if the notch position No. 1 is used. Thus, the plates in positions A, B, where the key has a completely semicircular cross-section, FIGS. 12A, B, must actuate plates having notches in position No. 1. In position C, the key has a cross-section reduced by 15 (FIG. 12C), which means that the notch of the corresponding lock plate must be in position No. 2. In position D, the key has a cross-section reduced by 30 (FIG. 12D), which means that the corresponding lock plate notch must be in position No. 3.

Upon reflection, it should be apparent that, if the key is turned in a direction wherein the lock plates are pushed by the reduced cross-sections of the key, each plate will be turned through a different arc until all of the notches are aligned to allow the locking pin 24 to drop into position. When the key is turned in the reverse direction, the edge of the key is uncut. Therefore, the edges of the crescent keyholes 42 are aligned,

which means that the notches are scrambled. The locking pin 24 is pushed out of the groove, and the cylinder 23 can no longer turn.

According to a further embodiment of the invention, the cap 20 is placed on the end of the tubular housing 21. Thereafter, the cap is placed top down in a cavity of a die which confines the cap and keeps it from expanding. Then a crimping tool with a circular cavity is lowered over the outside of the cap, at the open end thereof, to crimp it onto the housing. Thus, the open bottom of the cap is rolled inwardly, as at 82, 83 (FIG, 5). This crimping further prevents removal of the cap. In one embodiment, the threads may be retained on the outside of the housing 21; or, suitable retaining shoulders (not shown) may be formed on the housing.

. FIGS. 13 and 14 show a method of further protecting the lock. Here, a coin box or similar device 70 has the inventive lock 71 attached thereto. Positioned over the lock is a metal cap 73 having a keyhole-shaped opening 74 formed in the top. A relatively large diameter hole C enables passage of the key shank. However, this part of the hole is not over the crescent keyhole 42 in the cover plate. A cove of reduced diameter D is communicatingly offset from the large hole to receive an area E of reduced width on the key. Thus, the key must be inserted into the large part of the opening, as far as the start of the reduced area E, and then it is moved sideways into the smaller part of the opening D. At that point, the key may be pushed further into the crescent keyhole 42. The cap 73 makes it more difficult to work a pick in the lock.

The advantages of the lock should now be apparent. First, the hardened escutcheon or nose piece and the cover plate 62 cannot easily be drilled or cut. The ball bearing 38 keeps the lock from being drilled out completely. Second, the plates 22, 55 are not spring loaded; thus, there is no way for a person to hear or feel the tumblers drop into position. Third, it is difficult to work a pick in the crescent-shaped keyhole. Fourth, the piece parts are all made of screw machine tools or a punch press; therefore, the lock has a low cost and the cost of entry into the market is slight.

The invention provides room for many modifications. Thus, the appended claims should be construed to cover all equivalent structures falling within the true scope and spirit of the invention.

I claim: 1. A disk type lock comprising a housing, said housing being open at a key inserting end thereof and having a smooth bottom therein with a bearing seat at the end opposite said key inserting end,

the outside surface of said housing having a threaded periphery,

a lock cylinder having a bearing at the lower surface,

said lock cylinder slidingly fitting into said open end and cooperating with the bearing seat at the opposite end of the housing, whereby said cylinder is turnable in said smooth bore,

locking disks in said cylinder,

hardened cap means threadingly fitting over said threaded periphery to close said housing and secure said locking disks in position,

each of said locking disks having an arcuate key hole therein,

said arcuate key hole describing a semi-circle with a I ertures.

3. The lock of claim 2 wherein the outer surfaces of said cap means are arcuate except for the vertical face thereof.

4. The lock of claim l wherein each of said lock disks has a crescent-shaped keyhole therein.

5. The lock of claim 1 and hardened means in the bottom of said cylinder.

6. The lock of claim 5 wherein said hardened means is a ball bearing cemented in the bottom of said cylinder.

7. The lock of claim 1 wherein said cap means has a cross-sectional contour which has no wrench grasping surfaces thereon, said means for preventing said removal of said cap means comprises stake means whereby said cap means is staked through said cap and wherein said housing, and each of said lock plates has a crescent-shaped keyhole therein.

8. The lock of claim 7 and hardened means comprising a ball bearing cemented in the bottom of said cylinder.

9. The lock of claim 1 wherein the means for preventing said removal of said cap comprises crimped means integral to said cap means whereby said cap is crimp locked to said housing.

10. The lock of claim 1 wherein said cap means has a cross-sectional contour with no vertical surfaces thereon, said means for preventing said removal of said cap means comprises crimped means whereby said cap means is crimp locked over said periphery of said housing and staked through said cap and housing, and each of said lock disks has a crescent-shaped keyhole therein.

11. The lock of claim 1 wherein said means for preventing said removal of said cap means comprises an adhesive inserted between said cap means and said periphery.

12. The lock of claim 1 wherein said means for preventing said removal of said cap means comprises a metal housing positioned over the lock,

said housing having a keyhole opening therein aligned with the keyhole'opening of said lock, and

means for inserting the key for opening the lock through said housing keyhole opening into said lock keyhole.

UNITED 'd'l'A'i'i' lj Z'A'ibii 1 urrruxu CERTIFICATE OF- CGRRECTEON latent No. l 3,821,886 7 a a Dated July 2, 1974 Invent0r'(s) 4 Werner Ladewig Q Q It is certified that error appears in the above-identified patentand that said Letters Patent are hereby eorrected 'as shown below:

Column 6, line "17- Before Sai d" (first-occurrence) (Claim 7) cancel "wherein"; after""and" 1 insert j-- wherein 1 Signed and sealed this -9t h day 'of N vnib er 197'.

(SEAL) Attest:

McCOY M; GIBSON JR.

= c." MARSHALL DANN v Attesting Officer Commissioner of Patents F can eo-uoso (10-69) 

1. A disk type lock comprising a housing, said housing being open at a key inserting end thereof and having a smooth bottom therein with a bearing seat at the end opposite said key inserting end, the outside surface of said housing having a threaded periphery, a lock cylinder having a bearing at the lower surface, said lock cylinder slidingly fitting into said open end and cooperating with the bearing seat at the opposite end of the housing, whereby said cylinder is turnable in said smooth bore, locking disks in said cylinder, hardened cap means threadingly fitting over said threaded periphery to close said housing and secure said locking disks in position, each of said locking disks having an arcuate key hole therein, said arcuate key hole describing a semi-circle with a centrally located solid penninsular section extending into the semicircle, and means for preventing the removal of said cap means from said housing.
 2. The lock means of claim 1 wherein said means for preventing said removal of said cap means comprises a first aperture in said cap means, a second aperture in said lock cylinder aligned with said first aperture in said cap means, and stake means press fitted into said first and second apertures.
 3. The lock of claim 2 wherein the outer surfaces of said cap means are arcuate except for the vertical face thereof.
 4. The lock of claim 1 wherein each of said lock disks has a crescent-shaped keyhole therein.
 5. The lock of claim 1 and hardened means in the bottom of said cylinder.
 6. The lock of claim 5 wherein said hardened means is a ball bearing cemented in the bottom of said cylinder.
 7. The lock of claim 1 wherein said cap means has a cross-sectional contour which has no wrench grasping surfaces thereon, said means for preventing said removal of said cap means comprises stake means whereby said cap means is staked through said cap and wherein said housing, and each of said lock plates has a crescent-shaped keyhole therein.
 8. The lock of claim 7 and hardened means comprising a ball bearing cemented in the bottom of said cylinder.
 9. The lock of claim 1 wherein the means for preventing said removal of said cap comprises crimped means integral to said cap means whereby said cap is crimp locked to said housing.
 10. The lock of claim 1 wherein said cap means has a cross-sectional contour with no vertical surfaces thereon, said means for preventing said removal of said cap means comprises crimped means whereby said cap means is crimp locked over said periphery of said housing and staked through said cap and housing, and each of said lock disks has a crescent-shaped keyhole therein.
 11. The lock of claim 1 wherein said means for preventing said removal of said cap means comprises an adhesive inserted between said cap means and said periphery.
 12. The lock of claim 1 wherein said means for preventing said removal of said cap means comprises a metal housing positioned over the lock, said housing having a keyhole opening therein aligned with the keyhole opening of said lock, and means for inserting the key for opening the lock through said housing keyhole opening into said lock keyhole. 